form bubbles vs foam

form bubbles is not a noun while foam is a noun.

Word	Noun	Adjective	Verb	Adverb
form bubbles	No	No	Yes	No
foam	Yes	No	Yes	No

As verbs, form bubbles and foam are synonyms defined as:

Other synonyms of form bubbles include effervesce, fizz, froth, sparkle.

form bubbles (noun)	foam (noun)
	a mass of small bubbles formed in or on a liquid
	a lightweight material in cellular form; made by introducing gas bubbles during manufacture

form bubbles (verb)	foam (verb)
become bubbly or frothy or foaming	become bubbly or frothy or foaming